1. Field of the Invention
This invention relates to packaging techniques, and especially to techniques useful in producing vacuum or gas-filled packages for containing food products and the like. More particularly, this invention relates in one principal aspect to improved packaging apparatus and methods suitable for making packages of a class exemplified by the disclosure of U.S. Pat. No. 3,467,244.
2. Description of the Prior Art
A variety of packaging machines have been proposed and used over the past decade or so for vacuum packaging of food products including cheese, luncheon meat, bacon, frankfurters, and the like. The machines which have been used include rotary types, for example as shown in U.S. Pat. No. 2,888,787, and straight-line machines such as are shown in U.S. Pat. Nos. 3,061,984, 3,524,298 and 3,545,163.
The packaging machines available heretofore have not been fully satisfactory. In part, this is because the machines have not been capable of packaging an adequately wide range of products. Special problems are presented in packaging certain products, particularly sliced bacon.
Such problems, for example, stem from the fact that bacon typically is sliced and simultaneously placed in shingled formation by machines having involute-shaped knives rotating on horizontal axes, arranged to cut the bacon from above. In order for these machines to slice bacon cleanly, without tearing or separating fat from lean portions, the knife must enter from the lean (inside) side. Thus, the bacon necessarily leaves the slicing machine with its lean side up, and it has generally been found to be good practice to convey and handle the product with its lean side up, all of the way from the bacon press into the finished package.
Now, it is well established that the final package should be so arranged as to present to the customer a view of the lean side of the bacon, permitting customer inspection of the lean edges of the slices in a neat and uniform disposition. For best presentation, moreover, the display side of the package should be the side which has been thermoformed into a cup-like container for the bacon.
Some packaging machines, even though capable of making the especially preferred semi-rigid bacon package such as shown in U.S. Pat. No. 3,467,244, form the semi-rigid display side downward (i.e., so that the container opening faces up to receive the product). When such machines are used for packaging bacon, the bacon must be inverted before loading, in order to dispose the lean edges against the display side. This inverting procedure has not been satisfactory, particularly due to the dangers of disrupting the shingle arrangement during the loading operation.